Coaxial leadin for electron discharge devices



Dec. 7, 1948.

J. w. WEST COAXIAL LEADIN FOR ELECTRON DISCHARGE DEVICES 2 Sheets-Sheet1 Filed Oct.

lNl/ENTOl? J. W. WEST :4

A 7' TORNE v Dec. 7, 1948. .1. w. WEST 'COAXIAL LEADIN FOR ELECTRONDISCHARGE DEVICES 2 Sheets-Sheet 2 Filed Oct. 18, 1946 //Vl/EN7'OR J. W.WEST A T TOR/V5 V fiatented Dec. 7,

COAXIAL LEADIN FOR ELECTRON DISCHARGE DEVICES John W. West, JacksonHeights, N. Y., assignor to Bell Telephone Laboratories, Incorporated,New York, N. Y., a corporation of New York Application October 18, 1946,Serial No.704,075

This invention relates to electron discharge devices and moreparticularly to such devices for generating high power energy in highfrequency transmission systems.

In certain applications of power generatmg '5' electronic devices, theoperating voltages for the electrodes are supplied through coaxiallinesto obtain high efficiency and low loss in .the coopcrating circuitscoupled to the devices. Since the conductors of the devices are mutuallycoupled to the coaxial lines to simulate connective continuations of thelines to the electrodes of the device, certain mechanical straindifiiculties usually arise in the hermetic seals of the tubularconductors of the device connected to the internal electrodes. Thesedifiiculties occur particularly in the seals for high temperatureelectrodes, for example, the cathode, which is usually composed of aplurality of filamentary sections heated to flow in the operation of thedevice.

One object of this invention is to prevent deleterious temperaturestrains in the conductor seals of high power discharge devices.

Another object of the invention is to improve 25" vthe coupling of theelectrodes in the device to coaxial lines to reduce high frequencycurrent losses in the propagation of the energy supplied to the device.

A further object of the invention is to rigidly mount the electrodesdirectly on coaxial conductors sealed in one end of the device forcoupling to coaxial lines with low capacity interconnections.

Another object of the invention is to facilitate the mounting of thefilamentary cathode in the device to provide coaxial terminalscoextensive with the terminals of the other electrodes.

A further object relates to relieving temperature stresses in the jointsbetween metal and glass portions of the evacuated vessel whereby a longoperating life is assured.

These objects are realized in a typical embodiment of this invention inan external anode type discharge device including internal cooperatingelectrodes which are concentrically mounted within the anode. Theinternal electrodes are individually connected to external circuits bymetallic sleeve terminal conductors ofithe coaxial type which are sealedin nested relation to telescopic insulating sections disposedintermediate the con--' ductors, and the conductor assembly isjoined tothe anode by an insulated housing portion to segregate the low potentialconductors from the high potential anode.

The feature of this construction is the reduction 13 Claims. (Cl.250--27.5)

of the length of the device for a predetermined power output whilemaintaining the desired insulation resistance between adjacentconductors. This is accomplished by mounting the coaxial sleeveterminals in stepped relation about a central terminal and connectingadjacent terminals together by elongated insulating sections sealedadjacent opposite ends of the respective metallic walls of .the sleeveterminals to provide the required insulation paths between the nestedterminals.

Another feature of the invention relates to the mounting of theelectrodes on the sleeve terminal conductors to provide a rigid assemblywherein 1 the internal electrodes are held in proper concentric relationand substantiallybraced against misalignment by external shock orvibration. In a specific embodiment, a pair of cylindrical electrodesextending into the anode and uniformly emission temperature to supplycopious electron 20 spaced therefrom are individually joined to theouter pair of sleeve conductors by metallic conical shields which formbarriers between the low potential conductors and the portion of thehigh potential anode extending within the housing of the device.

Important features of the invention relate to the mounting of thefilamentary cathode in the device and the construction of the terminalstherefor so that the high heating temperatures inherently encountered inthe operation of the cathode do not adversely affect the compositehermetic seals at .the junction of the metal terminals and insulatingsections. In this construcn tion the cathode terminals comprise acentral plug member or standard surrounded by a metallic cup memberhaving the closed end spaced concentrically from one end of the plug byan internal telescopic insulating wall section which is hermeticallysealed to the inner end of the cup and the outer end of the plug member.The closed end of the cup member is provided with spaced radial slots topermit the closed portion of the cup to resiliently yield underexpansion and contraction clue to temperature changes so that 3 thedevice by reason of the coaxial position of the sleeve terminals on theend of the device. The coaxial sealing of the terminals in theinsulating sections of the vessel insures coaxial symmetry of theindividual electrodes supported thereon in relation to the surroundingelectron receiving surface of the external anode.

Still another feature of, the assembly relates. to the combination ofthe external anode with a large air-cooled heat radiator fixedly joinedto the anode and forming a protective enclosure for the sealed exhausttip on the end of the anode. This is accomplished by enclosing the anodein a metallic casing which provides a cavity or space for the sealingtip on one end of the anode and securing the anode in the radiatorcasing by fusible cadmium metal which also embeds the sealing tip in themetallic fusible mass in the cavity. The tip is, therefore, completelyprotected from injury and the metallic filling forms anikltermediatemass of low resistance and high thermal conductivity whichdissipates the heat ener y expended in the anode and efficientlytransmits it to the radiator.

These and other features of the invention will appear from aconsideration of the following ole-- tailed description when taken inconnection with the. accompanying drawings which illustrate theconstruction of one embodiment of the invention. In the drawing:

Fig. 1 is an elevational view in cross-section of a typical constructionof the device showing the assembly of the elemental parts;

Fig. 2- is'aplan view of the device of Fig. 1, with av portion only ofthe air-cooled radiator shown in full lines. showing the concentricarrangement of the conductors;

Fig. 3 is anenlar ed perspective view of the inal; portion; of theassembly with sections 1 e-seals broken away to illustrate the detailedcon truction;

Fig. 4 is a planviewof the cup terminal detail employed in the device ofFig. 1- illustrating the configuration. of the closed end of theterminal cup;

5 is a similar plan view of the cup terminal in combine-t n with thecentral plug: terminal on the line 5- .,5 of Fig. 1 to show theconnection. of the, filamentary assembly to these ermina and Fig. 6 is aperspective view of the filamentary cathodea-sd. terminal assembly em oie in e device pith-is invention illustrated in Fig. 1.

R fer in to the drawings and particul rly to Fig. .1. the high powerelectronic ischarge device of-this invention s embodiedin any externalanode air-cooled type of device having a heavy copper sleeve. orcylindrical portion 10 which forms the major section of the enclosingvessel and for convenience of, assembly is provided, with a separateclosure plate i], also of copper, which is brazed to. the bottom. of thecylinder by a high melting point solder. The closure plate H is providedwith a central aperture to receive a metallic .exhaust-tubulation I 2,the tubulation having a. flared; inner edge brazed to the inner surfaceof the closure and the outer surface of the closure being brazed to thetubulation, where it projects therefrom, by solder seal to prevent atthe joints between these members. The:tubulationv permits the pumpingand exhaust of: the internal discharge space of the device aftercomplete assembly to secure a high vacuum. Th tr bulation may be sealedoif at l3 after the desiredlow pressure is secured in the device.

4 The opposite end of the anode is machined on the outer surface toslightly reduce t e outer diameter to provide an internal tapered edgeand a positioning seat adjacent the outer boundary of anode for ametallic flanged ring 14 which is brazed to the copper anode at theouter surface of the anode. The ring 14 is preferably formed of steelhaving a. copper plating applied thereto and the flanged ring supports aflared sleeve l5, preferably of a low expansion metallic alloy havingthe composition of approximately 28 per cent nickel, 18 per cent cobaltand the remainder principally iron. The sleeve I5 is mounted coaxiallyabout the reentrant portion N5 of the anode and the flared portionextends divergently with respect to the tapered rim of the anode. In theassembly of these parts to the anode section, it is preferable to securethe sleeve l5 tothe flanged ring i4 prior to mounting the ring on theanode. This is accomplished by inserting a copper wire ring within thesleeve at the junction of the sleeve to the ring and heating the copperwire to fusion temperature to flow copper into the joint between thesleeve and the flange of the ring. The ring and sleeve assembly may thenbe brazed to the anode body. The nickeliron cobalt alloy is preferredfor the sleeve since this metal has a coefficient of expansion similarto glass or vitreous bulbous portion I! of the enclosing vessel which ishermetically sealed to the flared rim of the sleeve IS. The bulboussection 17 is preferably formed of a low expansion,

- mitti-ngenergy supplied by the'device, it is essential that thecouplingyof the device to these lines have a minimum energy losscomponent and avoid. the introduction of extraneous capacity andimpedance components so that the characteristics of the coordinatedlinesand device may be maintained at prescribed values. This is accomplishedy f rming the electrode terminals of the device separate sections of thecoaxial lines and mounting these. sections in cooperative relation tothe internal electrodes of the device and the insulating portions of thevessel so that these t rminal. sections intcrmesh with the lines and, inef ect, form direct .continuations of the lines to the electrodca.However, in order to achieve this result, it is essential that theinterrelation of the terminals with the device produce the requiredinsulation resistance between the several electrodes to derive efiicientcoupling and avoid theintrod-uction of temperature and mechanicalstrains or stresses in the terminal seals between the'conducti-ve andinsulative .parts of the device.

The-realization of'these factors constitutes one feature of thisinvention. The terminal conductors of the device of this invention aregrouped in coaxial relation on the insulating section I l of thevesselso that the coaxial lines may be readily combined with the deviceto couple the cooperatminals or conductor-s for the electrodes in the ofJ. E. Clark and V. L. Ronci.

device are a group of multiple, nested, sleeves or cylinders l8, I9 and20 mounted in stepped and coaxial relation about a central terminal orstandard 2|. The several conductors are insulatingly spaced in properposition by insulating walls which are mounted intelescopic relationbetween the sleeve terminals, to form a completely enclosed containingvessel for the internal electrodes. The sleeve terminal conductors areconcentricallymounted both with respect to each other, with the axialstandard 2| and the glass vessel section I! by hard glass bell-shapedsections 22, 23 and 24 which are interposed in telescopic relationbetween adjacent sleeve conductors I8 and I9 and 20 and between theinterior of conductor 20 and the central standard 2 The glassbell-shaped sections and the sleeve conductors are arranged in nestedrelation to reduce the over-all length of the device, to provideinternalcoaxial supports for the electrodes within the device andexternal contact portions for coupling to coaxial lines for supplyingthe operating voltages to the internal electrodes. In this construction,the sleeves progressively extend from the terminal end of the device instepped relation so that the sleeve conductor l8 projects a shortdistance beyond the end of the glass vessel section H, the sleeve 20extends the furthest from the end of the vessel and the sleeve l9extends in a position intermediate the respective terminals on oppositesides thereof. The central standard 2| and the respective sleeveterminals Ill to 20 inclusive, are preferably formed of thenickel-iron-cobalt alloy similar to the sleeve l5 so that theseterminals can readily be sealed to the borosilicate glass sectionsinterposed therebetween and will have temperature coefiicients matchingthe coefiicients of the glass sections. The outer end of the glasssection 24 is hermetically sealed to the cylindrical surface of thecentral column or standard 2| adjacent the outer end while the inner endof the section 24 is sealed to the inner wall of the sleeve 20. Thelatter is provided with a platform closure portion 25 having a centralopening or aperture 26 through which the central standard 2| projects,the flared end of the glass section 24 being sealed to the inner wall ofthe sleeve 20 adjacent the platform 25. The bell section 23 is sealed toan intermediate portion of the outer wall of the sleeve 2|! and theflared end is sealed to the inner wall of the sleeve I9 adjacent theinner end thereof. The bell section 22 is sealed to the outer Wall ofthe sleeve l9 adjacent the outer end and the flared rim of the sectionis sealed to the inner wall of the sleeve |8 adjacent the inner end. Thecombined terminal assembly is sealed to the glass section H by joiningthis glass section to an outer intermediate wall portion of sleeve l8.The inner flared seals of the bell-shaped glass sections to therespective sleeve terminals may be performed in accordance with themethod disclosed in the application Serial No. 434,520 filed March 13,1942 The central standard 2| may be provided with a copper terminal head21 which is brazed to the outer end of the standard by a high meltingpoint solder, such as 20 per cent silver and 80 per cent copper whichhas a melting point of 910 C. the head being flush with the end of thesleeve terminal 20. It will be noted, in the nested combination of theinsulated spacer sections and the sleeve terminals that the conductivesleeves form shield- .ing-members between successive insulating spacersection s,. not only to protect the insulating sec- '6 tions fromconducting charges within the discharge space but also to protect theSect n against mechanical injury from external causes.

In the device as shown in the embodiment of the invention, a pair ofcoaxial grid electrodes are mounted within the anode in coaxial spacedrelation thereto and also to an enclosed electron emitting source in theform of a multi-strand filament assembly. The composite sleeve terminalassembly not only intermeshes with the coaxial lines of the system butalso on the inner end rigidly mounts the internal electrodes in coaxialrelation to the anode surface. The cathode assembly includes fourstrands 28, 29, 3|] and 3|, as shown in Fig. 6, which are formed ofthoriated tungsten ofsufiicient diameter to form a self-supportingstructure and capable of consuming the current supplied thereto to raisethe strands to high temperature for the emission of electrons across thedischarge space, to the anode. These strands are provided with gooseneckend portions 32 which are joined together at the center bya tungstenhelix 33 which welds the four sections into a box-like frame to maintainthe strands in uniform lateral relation.

The strands are interconnected in parallel relation to the centralstandard 2| and the platform 25 of the cup-shaped sleeve 2|] by a pairof molybdenum studs 34 which are welded in sockets 35 in off-centerrelation in the top surface of the standard 2|. Another pair ofmolybdenum studs 36 are mounted in off-center relation on the platform25 in apertures 37 of the platform and are reenforced at the junctionwith the platform by nickel eyelets 38, to improve the welded joint atthe thin wall of the platform 25. The filament strands are joined to thestud rock by embracing molybdenum collars 39, to rigidly support theframe filament assembly from the platform and central standard.

A cylindrical control grid surrounds the filament assembly and is formedof upright spaced molybdenum wires 40 having a uniformly pitched helix4| of small diameter molybdenum wire wound around the support wires andwelded thereto to form a cylindrical grid structure. The lower end ofthe grid structure is reenforced by a heat shield or disc 42, forexample, of tantalum, andthe opposite ends of the support wires 40 arewelded to a nickel collar 43which is attached to the inner surfaces ofthe support wires and forms a base ring support for the grid structure.The control grid assembly is mounted in coaxial relation to the cathodeassembly by a truncated conical shield 44 of nickel-iron-cobalt alloyhaving a turned ring portion 45 at the smaller diameter end whichembraces the terminal end of the grid assembly and in conjunction withthe ring 43 welds the grid frame to a rigid mounting assembly. Theshield 44 is also provided with a turned rim 46 at the large diameterend" which extends around the inner rim of the sleeve terminal |9 and isWelded thereto.

A screen grid or accelerating electrode coaxially surrounds the controlgrid and is formed of a plurality of upright support wires 41,preferably of molybdenum, supporting a uniformly spaced grid helix 48,also of molybdenum wire having the same diameter as the helix 4| on thecontrol grid. The inner end of this grid is closed by a tantalum discshield 49 and the supporting end carries a nickel sleeve or rim 50 onthe inner surfaces of the support Wires 41 to assure the cylindricalalignment of the grid supports. The accelerator grid is coaxially spacedaround the 7 ontrol grid and uniform]yspacedfrom the inner surfaceof'the-anode l by-a truncated Cb'n'i al shield of 'nickel 'iron -cbballtalley;"havln'gi rin'g'extens'ion 5-2 at the "smalle" diameter 'andembracing the" grid support To ds 4 "and the associated nickel ringfill"to whiclf'it vlrelded. The *larger diameter end (if the shield "is pro-"vided'with a flanged "lip 53 which "embraces the inner "end ofthe'sleev'e conductor ligand iswelde'd thereto. This arrangementprdvid'es eo'afiial sym' metry'for the mounting-of the interri'aieeetro'des in the anode andrigid'ly'maiii'taii'i's the elettrodes intheir prescribed r'ela'tion' "regardless of tem: perature'variations inthe d'eyl'ce; 'The fco akia-lly spacedeonio'a'l shields also' -fornisu'dcessiy'ebarrier's between the tapered-edgeoithe anode-6X tendingwithinthe-vessel'hf the de'v'iean'd'the low potential conductors-of theCathode assembly so thatarcin'g is prevented"aeross thisfiatliwithrespect to the a-n'edesurfaee and the'rebymaf 1 teriallyprolongs the? operating -'-life of the device due to the absenceof'sjhofts between the Closely spaced elect'rbdes within theenclesing*vessel. Anotherin ipoit'aht feature of the 1 "vention -rem theglass tofmetal seals at'the 'junct'inof the glass -section '24 and "the"cup' shap'ed terminal member in view O'f the high temperaturein posedon these joints; -partiulafly at'thje inner joint close "to the'='conduotingj studs of 'the'ffila' me'ntafy assembly. Thestresses-and'stfairi's alttendant upon varying temperature'conditions atthe seale'd jointare' overcomefin aocoldande ith a feature of thisinvention, b nna-5g thefli igtform substantially yieldablesotha'ttenipera' ture changes I are dissipated "in the ineta'l f'ratherthan being transmitted to the hermetic Seal" at the inner end of" theten-sha d" ectio n za. The top of the p1atfo1"m"2'5 is firoiridedwithspaced circular openin'g st lfas shown in-Figsflifand '5 connectedwith the large di anieten'central'opening -rm by short slotsvyfhih'xtehdf'iadi ally between the "larger diameter 'openi'n'gsin "theplatform. In addition to-these" slots the outer boundaries of theapertures 54 are sl'ott d as shown at 56,'and theseslots; as sho uinfinF gi3 extend beyond the edge'o'f the pas oral and partially along" the"cylindiioal' sur'facie of the sleeve 'p'ei'tion' 20 of "the terminal.Thejradiai slots and 'spaced" apertures across the transverse dimensionof the-platform 25 pro ide vi wable segments in the 'ciip 'shapdt'ermtnal 'f the cat'l'iode"assenibly"which expand and eont act withtemperature changes in the high temperature structure'of the cathode andthereby p 'e vent such changes, ortheeffets of suoh changes, reaehing'the her netie seal adjacent the inner end] of the-Cup terminal.Henbejleaks' ot fiiaetures 0f the glass are eliminated and' thefjyacuilmtype s'eal'of the-glass joint ispi e' s'eiived'to in: sure maximumoperating life for'the "combihed structure; W v I I I The heat energygneiated injthe anode due to the 1 high operating pote'ntial'itiesfofthe device is efiicientlydissibated hy "air-eoolihg and thi s involves alarge surfacej adiator assembly'xyhich completely enclosestheouteranodeseetifin ofthe device. This radiato inclu'de s' ac'oppefisleeve casing -51 of slightly larger diametetfthan theext'efnaldiamete'r of theandde; "The sl'eve pbr fiioiibfthe CaSiiigabuts againstthe flanged "TIM 7 M on the *anode', the sleeve being ofsufitin't length to form a proteeting WalI arQuiid' the sealing tipl'2-'*of theanode; The' cas'ing i's"si1rmoundedty "a cylindrical"assembly" of "spaced coppefradiatihg fihs 58 "whiChmaybe seeui'e'd tothec'asing =51;in-accordanee with themetnods disclosed in'ihyp'rior'Patent 2,341,752," issued-Febru'ary" 15, 19441 The radiatorassembly is s'e- Cured to the *a'nodeby a fusible"fi1lirig"of *i'pwthermal resistance "and high thermal conductivity metal 5 9 ,"suclrascadmium, haying a -i'xielt' mg "p'oint' of 1 approximately 320 0., whichfidw's between 'the' walls of the casing "and Y anode to ri idly "affixtheradiator tothe' a ode and forms a solidr'n'ass "of 'nie'tal"'aroiihdthe sealing tip (2 'Whl'h 'is-embedde'd in the massand plotebted from"injury fr'om external causes; The bottom of thehasih'ginaybe closed byacoVerBOflQlso of "bpper; to "provide a finished appeal'anlfe fortheassemb'ly. I

While "the invention "has been disclosed "with iSpet 0 2 513601116mbfidili'iht' of related "E trades in theuevice; it is ofc'ourseyun'derswod thatvari'ous' modifications may be 'li'nade in thenumber of electrodes combined in thejassembiy orih thenblnb'inati'on ofthe *detail'ed parts' of the construction Without departing fromth'fscope of the "invention as defined in bhe appended cla ms;

'Wh'atis clair'n'edis: I H 1. A'n el'e'ctro'n dis(311ait??? 'uevic'ecdmfirlsinfg vessel elm-losing "a plurality'of eleotfodesfleono'ent'fi'ctubular 'ooi'iduetors 'ihsulitii'i'glftaild to said-"vessel; saidelectrodes being' eonnecte tbfsaid tors'and yieldable means extendinacf'dss one at "said cond'uetors to relieve tempeiiap r'e st'rain'sinthe'sealed insulating j'ointadjaeeht the junotfon withsaidone'ndu'ctorgI 2. An." electron discharge "devit'e'combn'sing vessel enclosingplurality-0f electrodes,jconcng t'rictubular 'e oii'duct'orsinsulatingly sealed to sf'ai d tresselffsaid electrodes being conneotedto said conductormnd the-inneftubu'iaic nductor? avi ing inte''ia'ltransverse *pnrtion eateiqidi g mass-15h end, said transverse p'tionfhajinga pluralit'y'of yielda hle' segniehts t i ete' ten pe1f+atdie strains ih"the"sfea1'ed' insulat g 'j oi nt adj cent thefiunctiowith saidinnei con ll'CtQIt, I i H ing said terminal to said anodeportion, an electrode within said anode portion and supported by saidterminal, a cathode axially mounted in relation to said electrode, acup-shaped terminal coaxially within said tubular terminal, a centralsolid metallic terminal extending through said cup-shaped terminal, saidcathode being connected to said cup-shaped and central terminals, andinterconnecting insulating sections sealed between said central,cup-shaped and tubular terminals and surrounded thereby.

6. An electron discharge device comprising a hollow metallic anodeportion, a tubular conductor, an insulating enclosing vessel portionjoining said conductor to said anode portion, an electrode within saidanode portion and supported by said conductor, a cathode axially mountedin relation to said electrode, a cup-shaped terminal coaxially withinsaid tubular conductor, a central solid metallic terminal extendingthrough said cupshaped terminal, said cathode being connected to saidcup-shaped and central terminals, and interconnecting glass cup sectionshaving opposite ends hermetically sealed to the respective adjacentwalls of said conductor and terminals within and between which they aresituated.

7. An electron discharge device comprising a vessel enclosing aplurality of electrodes including a multi-section filamentary assembly,concentric conductors insulatingly sealed to said vessel and supportingsaid electrodes, one of said conductors being an inverted cup-shapedmember having a central aperture, alternate sections of said filamentaryassembly being attached thereto, a central plug member extending throughsaid cupshaped member and supporting the remaining sections of saidfilamentary assembly, and a vitreous seal portion extending between saidcupshaped member and central plug, said cup having peripheral slotstherein to relieve stresses in the vitreous seal adjacent thereto.

8. An electron discharge service comprising an enclosing vessel, aplurality of electrodes therein, concentric cylindrical conductors atone end of said vessel, said electrodes being individually supported bysaid conductors, and bell-shaped glass sections interposed between saidconductors, the inner ends of said sections being sealed to the interiorinner walls of said conductors and the outer ends being sealed to theexterior outer walls of adjacent conductors.

9. An electron discharge device comprising an enclosing vessel, ananode, a filamentary cathode within said anode,aterminal support forsaidcathode including a metallic cup-shaped member having a centralaperture, a metallic conductor extending through said aperture,connectors joining said cathode to said member and conductor, andinsulating sections forming part of said vessel sealed between saidconductor and cup-shaped member and between said cup-shaped member andvessel, said cup-shaped member having spaced openings adjacent saidcentral aperture and radial slots extending from said aperture andbeyond the closed edge of said member.

10. An electron discharge device comprising an enclosing vessel, ananode, a multi-strand filamentary cathode within said anode, a terminalsupport for said cathode including a metallic cup-shaped member having acentral aperture, a metallic standard extending through said aperture,insulating sections forming part of said vessel sealed between saidstandard and cup-shaped member and between said cup-shaped member andsaid vessel, and a pair of rigid supports extending from each saidstandard and cup-shaped member and joined to said multi-strand cathode.

11. An electron discharge device comprising an enclosing vessel having ahollow anode portion, a metallic sealing tip extending from said anodeportion, cooperating electrodes within said anode portion, conductorssealed on one end of said vessel supporting said cooperating electrodestherein, a protective casing surrounding said anode and tip, a pluralityof radiator fins mounted externally on said casing, and a solder fillingjoining said casing to said anode and embedding said tip within saidcasing.

12. An electron discharge device comprising an enclosing vessel having ahollow anode portion, an annular flange member afiixed to said anodeadjacent one end, a metallic sealing tip extending from the opposite endof said anode portion, cooperating electrodes Within said anode portion,conductors supporting said cooperating electrodes therein, an insulatingportion of said vessel sealing said conductors to said flange member, ametallic casing surrounding said anode and having a cavity enclosingsaid tip, said casing being in contact with said flange member, afilling of cadmium metal joining said casing to said anode and embeddingsaid tip in said cavity, and a closure for said casing adjacent thefilling mass of metal.

13. A connector for electron discharge devices comprising a plurality ofcoaxial cylindrical conductors disposed one within another and inlaterally spaced relation, and a plurality of insulating spacers eachdisposed between two adjacent conductors, each of said spacers includingan elongated cylindrical portion spaced from the respective adjacentconductors and end portions sealed hermetically to the respectiveadjacent conductors.

JQHN W. WEST.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number

